Helicopter crews from a San Diego-based ship and Marines from Camp Pendleton today were planning to join a flood relief effort in monsoon-struck Pakistan.

Nineteen cargo-carrying helicopters were on board the amphibious assault ship Peleliu and other ships in a strike group now in international waters off Pakistan, according to a Pentagon announcement.

Marines from the 15th Marine Expeditionary Unit are aboard the same ships, according to reports.

The Navy and Marine Corps helicopter crews were planning to relieve a half-dozen Army helicopter crews that have been bringing supplies to flood- stricken areas.

The Peleliu strike group and the 15th Marine Expeditionary Unit were already on a training mission in the Western Pacific, according to the Pentagon.

Defense Secretary Robert M. Gates announced Wednesday the Peleliu is off Pakistan’s port city of Karachi and will provide airlift assistance.

The Peleliu can provide significantly more rotary wing support, Gates said in a statement issued Wednesday by the Pentagon. Gates also said the USS Kearsarge — another helicopter landing ship — is headed to Pakistan to relieve the Peleliu.

“Pakistan is our friend and ally, and in their time of need, we’re committed to partnering with their government and military,” Marine Gen. James Mattis, commander of the U.S. Central Command, said in a U.S. Central Command statement.

Despite bad weather, six helicopter crews in partnership with Pakistani military have rescued more than 3,000 people and transported more than 300,000 pounds of relief supplies to flood-stricken areas of Pakistan since Aug. 5, according to U.S. Central Command.